Long Term Evolution (LTE) technology is a Fourth Generation (4G) wireless cellular communication technology. The LTE uses an Orthogonal Frequency Division Multiplexing (OFDM) technology, and time-frequency resources formed by subcarriers and OFDM symbols constitute wireless physical resources of an LTE system. Data of the LTE are carried on the wireless physical resources for transmission. The more the data information transmitted on the same amount of physical resources, the higher the transmission efficiency of the system.
In LTE uplink and downlink transmission, reference signal needs to be transmitted. The reference signal or pilot channel transmits data, known to a receiving end, for channel estimation at the receiving end. The known data are not data that needs to be demodulated at the receiving end, but the known data occupy physical resources, thus reducing the physical resource utilization of the system and further reducing the spectral efficiency of the system. How to reduce the physical resources occupied by the reference signal is an issue worthy of being studied and solved.
Moreover, for some wireless environments, the density of the reference signal can be reduced. If the system uses reference signal with high density, then in these wireless channel environments, the physical resources will be wasted, thereby reducing the system spectral efficiency. However, for some wireless environments, reference signal with higher density is required. If the system uses reference signal with low density, then a precision requirement of channel estimation cannot be met. How to avoid waste of the physical resources and meet the precision requirement of the channel estimation is also an issue worthy of being studied and solved.
In addition, with the development of communications and the higher demand on system performance, control information that needs to be sent by a sending end will become more and more. For example, Network-Assisted Interference Cancellation and Suppression (NAICS), which is a topic currently discussed in the 3rd Generation Partner Project (3GPP) conference, requires a network side to send a lot of interference control information to a terminal to improve demodulation performance of the terminal. However, too much control information sent by the system will occupy a lot of physical resources. How to make full use of physical resources to send more control information is also an issue worthy of being studied and solved.
Now major companies begin to study the wireless communication Fifth Generation (5G) technology to expect to better improve the time-frequency resource utilization, thereby improving system efficiency. Therefore, it is of great significance to study and propose better ways to solve multiple technical issues described above.